MAS2808 Piezo Driver: High-Voltage Alerts for Safety and Wearables

Introduction – Why Compact High-Voltage Drivers Are Key to Embedded Safety Feedback

In many safety-critical systems—whether medical monitors, smart alarms, or compact personal wearables—reliable, high-voltage actuation is essential for audible alerts, haptic feedback, or atomisation. But the design challenge is clear: engineers must deliver high-energy output from a low-voltage supply, within constrained footprints and power budgets.

The MAS2808 from Micro Analog Systems offers a dedicated solution. With an integrated high-efficiency boost converter, short-circuit-protected differential driver outputs, and both pin-based and I²C-selectable output voltages, the MAS2808 is ideally suited to safety sounders, atomisers, and low-power devices that demand strong user feedback—without the bulk or complexity of external driver circuitry.

This article explores the MAS2808 in depth and shows how it addresses common design constraints in embedded safety and alerting systems.

MAS2808 Key Features – Designed for Safety and Efficiency in Low-Power Systems

The MAS2808 is purpose-built to deliver high-voltage actuation in compact embedded systems. Its architecture combines a fully integrated boost converter with a differential piezo driver stage, supporting both single-ended and BTL configurations for maximum output swing.

High-Voltage Output from Low Supply

• Operates from 2.6V to 5.5V input supply

• Integrated DC/DC boost converter delivers up to 30V output, enabling up to 60V_pp differential drive

• Eliminates the need for an external Schottky diode or high-voltage power rail

Flexible Voltage Control: Pin or I²C

• 4-level output voltage selection via simple SCL/SDA pin states for minimal MCU overhead

• 8-level voltage selection via I²C interface for dynamic control and calibration

• I²C device address is 0x76; supports OVC programming for output voltage selection from 9V to 30V

Safety-First Power Management

• Soft-start mechanism to limit inrush current

• Piezo output short-circuit protection

• Thermal shutdown and undervoltage lockout to prevent malfunction during fault conditions

• Extremely low leakage current (<0.5 µA) when disabled via the EN pin

Minimal External Components

• Internal switching FETs reduce external BOM

• Recommended with small shielded inductors (2.2–2.7 µH) and ceramic capacitors

• No high-voltage routing or external driver stage required, simplifying PCB layout and EMI control

Together, these features make the MAS2808 an ideal drop-in solution for designers who need robust high-voltage actuation—without compromising board space, cost, or power efficiency.

Example Use Cases – Audible and Haptic Feedback for Safety and Alerts

The MAS2808’s unique combination of high-voltage drive, compact footprint, and ultra-low standby current makes it ideal for a range of safety-focused embedded applications, particularly in battery-powered or space-constrained devices.

1. Smoke and Gas Alarms – Loud, High-Integrity Alerts

In alarm systems, ensuring the user hears a fault condition is paramount. The MAS2808 can drive a piezo sounder at up to 60Vpp, generating high sound pressure levels (SPL) from a 3V coin cell or lithium-ion battery. With its soft-start boost converter and thermal protections, the IC maintains safe operation even during long alert cycles or fault conditions like shorted transducers.

2. Medical Wearables – Haptic Feedback in Compact Form

Devices such as portable blood glucose meters, pulse oximeters, or medication reminders often use haptic or audible prompts to assist users with impaired vision or during timed dosing cycles. The MAS2808 supports low-leakage standby (40nA), simple MCU interfacing, and flexible I²C voltage control, making it suitable for wearables with demanding power budgets.

3. Smart Tags and Trackers – Discreet Alerts, Long Battery Life

For asset tracking devices or personal safety tags, the MAS2808 allows short, sharp vibration bursts or tone playback without constant MCU supervision. Its low quiescent current and flexible enable control (EN pin) help prolong standby life while maintaining rapid wake-up and response.

4. Atomisers and Dispensers – Compact High-Voltage Drive

Ultrasonic atomisers for air fresheners, disinfectant sprayers, or portable nebulisers require high-voltage drive for piezo ceramics. The MAS2808’s integrated boost stage and programmable output voltage mean it can replace discrete multi-IC circuits with a single IC solution, reducing system complexity.

Key Specifications and Configuration Options

The MAS2808 combines flexible configuration with robust analogue performance. Below is a summary of its core specifications and programmable features:

Electrical & Mechanical Characteristics

Parameter	Value / Range
Supply Voltage (VDD)	2.6V to 5.5V
Max Output Voltage (Differential)	60Vpp (30V × 2)
Output Voltage Settings	4 steps (pin control), 8 steps (I²C)
Quiescent Current (EN = LOW)	< 0.5 µA
Operating Temperature Range	-40°C to +85°C
Package	TSSOP-16 (samples), DFN-12 (planned)
Piezo Driver Configuration	Single-ended or BTL (VOP/VON)

Output Voltage Control

Pin Control Mode (Default):

SCL	SDA	VOUT
Low	Low	30V
High	Low	24V
High	High	17.5V
Low	High	15V

I²C Control Mode:

OVC[2:0]	VOUT
0x00	9V
0x01	12V
0x02	15V
0x03	17.5V
0x04	20V
0x05	24V
0x06	27V
0x07	30V

• I²C address: 0x76

• I²C mode enabled when both EN and DIN are HIGH

• Compatible with 1.2V–5V logic levels

This versatile setup allows designers to finely tune the piezo output level based on sounder size, desired SPL, or user feedback intensity.

Design Considerations – Efficiency, Protection and Integration Tips

While the MAS2808 simplifies high-voltage actuation, optimal implementation requires thoughtful hardware integration. Below are key design guidelines to maximise performance and reliability in safety-critical or battery-powered systems.

Inductor and Capacitor Selection

The boost converter requires only a 2.2–2.7 µH inductor, depending on the power source. A shielded inductor is recommended to minimise EMI in compact designs, particularly in wearables or medical devices.

• CIN recommendations:

  • USB-powered systems: ≥47 µF

  • Coin cell: 100 µF recommended to mitigate ripple

• COUT recommendations:

  • Rated ≥35V ceramic capacitors

  • ≥1 µF for general loads; increase for high SPL transducers

Protection Against Transducer-Induced Surges

In harsh environments, piezo elements can generate reverse voltage spikes under mechanical or thermal shock. For such applications (e.g. smoke alarms mounted near industrial fans or compressors), external Zener protection is advised across the VOP and VON outputs.

• Use Zener diodes rated just above nominal output (e.g. 32V for 30V VOUT) to suppress surges without reducing drive voltage.

Ultra-Low Power Applications

The MAS2808 draws just 40nA in shutdown mode, making it ideal for long-term standby applications. Designers can disable the device via the EN pin, and re-enable it dynamically only when audio or haptic feedback is needed.

• Supports logic high threshold as low as 0.9V, making it compatible with 1.2V or 1.8V microcontroller logic levels.

Compact PCB Layout

• Keep CIN, COUT, and the inductor physically close to the IC to reduce trace inductance.

• Minimise routing to the SW and VOUT pins, which carry switching currents.

• VDD can use a narrower trace, as current draw is minimal.

These practices ensure clean operation, minimal voltage ripple, and improved efficiency—particularly valuable in safety-critical environments where reliability and system uptime are paramount.

Conclusion – Enabling Smart, Safe Feedback with the MAS2808

From high-decibel safety alarms to subtle haptic cues in medical and wearable devices, the MAS2808 enables reliable, high-voltage piezo actuation from compact, low-power systems. Its integrated boost converter, differential driver outputs, and flexible voltage control options make it a strong fit for engineers tackling alerting, atomisation or feedback design challenges—especially where board space, power budget and response time are limited.

With support for both pin-mode and I²C programmable output, low leakage current in standby, and integrated protection features, it allows OEMs to embed consistent, responsive feedback mechanisms into their devices without resorting to complex discrete circuits.

For developers seeking to integrate audible or tactile safety features into their next design, the MAS2808 offers a streamlined, high-efficiency path to implementation.

Contact Ineltek to request samples, a reference circuit, or a technical briefing on how the MAS2808 could enhance your next safety-critical embedded design.